I notice you have an incubatoir. Don't build for the minimum number of chickens. That would be a mistake.
The rule of thumb is one nest for every four hens. Most will lay in the same one, but there have been times when an extra one comes in handy, if you have broody, for instance. For 8 to 10 hens, I'd build 3.
The rule of thumb on here is a MINIMUM of 4 square feet per chicken in the coop and 10 square feet per chicken in the run. There are a lot of different things that go into these numbers. Some people get by with less, but some people try less and run into trouble. If chickens are too crowded, they can become cannibals. That's why a lot of commercial operations that really crowd their laying hens automatically trim their top beaks so they don't eat each other.
There are diminishing returns at some point, but your chickens are usually a lot happier if they have plenty of room. You will find that they are also easier to manage if they have plenty of room. One example is their poop. They poop a lot. If they are packed in fairly tightly, you have to manage that poop on a regular basis. If they have lots of room, you have to manage that poop a whole lot less often.
The reason Teach1rusl said an 8' x 8' is about the same cost as an 8' x 6' is that most building material comes in 4' or 8' dimensions. You will use a little more material, like maybe one extra sheet of siding and possibly some roofing material, but you will also have less waste and less cutting. And with that incubator, I'm not convinced 8' x 8' is big enough. Those incubators are dangerous. I know. I'm adjusting my temperatures now.